It is known to provide a system for automatically optimizing the heating curve of a circulating fluid heater or a heating circuit of a heating plant or apparatus for space heating purposes, e.g. of a building, the building zone or the like, in which the temperature to which a fluid is heated is a function of the ambient or external temperature and this relationship is defined by the heating curve.
The principles of such a system are applicable to any heating system in which the temperature of a fluid used to directly or indirectly heat a space, is raised in accordance with the exterior temperature in dependence upon a heating curve.
In French Pat. No. 1,461,767, for example, the automatic optimization of the heating curve is provided by controlling the room temperature and adjusting at least one parameter of the heating curve in dependence upon deviations from the setpoint or control parameter automatically in the sense that these deviations are reduced.
A heating curve is thus automatically approximated by the values of the heating supplied to the space-heating system and after some time, control of the room temperature can be terminated and further regulation of the temperature of the heating fluid can result exclusively in dependence upon the exterior temperature.
Put otherwise, once an optimum heating curve is established for a particular location, the heating system can initially be controlled in accordance with the heating curve, the interior temperature can be measured and deviations of the measured value from the predicted or setpoint value of the heating curve can be established, the heating curve adjusted in accordance with these measured values to minimize the deviation and thereby being optimized, and further control of the heating effected exclusively as a function of the external temperature in accordance with the optimized heating curve obtained by minimizing the deviations.
While this system is supposed to operate well where there are no perturbations, unpredictable effects are generally encountered in practice. For example, an unforeseeable event which would disturb the optimization of the heating curve can be the opening or closing of a window at unpredictable and random time intervals.
In practice, therefore, it is desirable to automatically optimize the heating curve by which a space is heated even where perturbations of the aforedescribed type may be encountered, i.e. where unpredictable events may cause dislocation of the room temperature and hence place unpredictable demands on the heating system at temporally unforeseeable points and to unforeseeable degrees. The advantage, of course, of optimizing the heating curve is to make the control of the heating operations less sensitive to such perturbations. In the past, systems for controlling the temperature of a given space in accordance with external temperatures have not been of a type which could allow automatic optimization with modern electronics such as microprocessors and microprocessor circuitry.